Under the power transfer deal, drawn up by the six-member Gulf Cooperation Council, Saleh will receive immunity from prosecution after transferring power to his deputy.

The state news agency Saba reported:

“The president ... arrived this morning in Riyadh on a visit to the Kingdom of Saudi Arabia, following an invitation from the Saudi leadership, to attend the signing of the Gulf initiative and its operational mechanism."

Figures from Yemen’s opposition, which has already signed the Gulf plan, have been invited to watch Saleh resign, Reuters reported.

The move comes after months of anti-governments protests left Yemen in a political deadlock, and after Saleh, who has held power for 33 years, repeatedly backed out of the deal.

It also comes after Benomar, with support from the United States and European diplomats, devised a compromise to implement the deal, Reuters reported.

Yemen, regarded by the West as a front line against al Qaeda, has been seen a revival of conflicts with Islamist militants and separatists, which have led to fears of civil war.